Download or read book The Effects of Dissolved Organic Carbon on Pathways of Energy Flow Resource Availability and Consumer Biomass in Nutrient poor Boreal Lakes written by Joseph Tonin and published by . This book was released on 2019 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Over the past few decades, terrestrially derived dissolved organic carbon (DOC) has been recognized as a fundamental driver of food web productivity in nutrient poor lakes. The mechanisms that underlie these effects remain poorly understood, particularly for higher trophic levels including zooplankton, benthic invertebrates, and fish. In a survey of eight lakes in northwestern Ontario, I determined consumer biomass and used stable isotopes of carbon, nitrogen, and hydrogen to investigate relationships between DOC and pathways of energy flow, resource and habitat availability, and consumer biomass. Using Bayesian stable isotope mixing models, I found that hypolimnetic phytoplankton were an important resource for zooplankton in low-DOC lakes. With increased DOC concentrations, light attenuation increased and chlorophyll a concentrations below the thermocline were reduced relative to epilimnetic concentrations. At higher DOC concentrations, zooplankton acquired proportionately more energy from low quality terrestrial sources. Zooplankton biomass also declined with increasing utilization of terrestrial sources (allochthony), suggesting that terrestrial organic matter suppresses zooplankton productivity through simultaneous limitations on habitat and resource availability and quality. Based on biomass, the dominant fish species across my study lakes was White Sucker (Catostomus commersonnii). Bayesian mixing models indicated that allochthony by White Suckers increased with DOC and that greater allochthony was related to lower White Sucker biomass measured as catch-per-unit-effort (bCPUE). Both White Sucker bCPUE and chironomid biomass were positively related to mean light irradiance, with the highest biomasses of fish and chironomids occurring in lakes with a higher proportion of their volume in the photic zone. White Sucker bCPUE was strongly and positively correlated with chironomid biomass, suggesting that DOC-mediated resource limitation may influence fish productivity via reduced prey availability.
Download or read book Does Dissolved Organic Matter Impact Primary Production A Study on the Effects of Terrestrially Derived Dissolved Organic Matter on Primary Production in Nutrient poor Boreal Lakes written by Bryanna Sherbo and published by . This book was released on 2020 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Over the past few decades, spatial and temporal variation in concentrations of allochthonous dissolved organic carbon (DOC) has been increasing in surface waters of boreal lakes around the world with climate change. Terrestrial landscapes export large amounts of organic matter into lakes, primarily as DOC. It is understood that DOC impacts primary production through its combined effects on light and nutrient availability. However, there remains uncertainty as to the mechanisms that cause DOC to have positive or negative effects on algal productivity. In a survey of 6-7 lakes spanning a DOC gradient (3.5-9.4 mg L-1) at International Institute of Sustainable Development-Experimental Lakes Area (IISD-ELA) in northwestern Ontario, we determined the effects of DOC on whole-lake metabolism (gross primary production (GPP), respiration, and net ecosystem production (NEP)) and depth integrated net primary production (NPP). Using in situ diel free-water oxygen method and in vitro partial pressure of CO2 incubations, we found that primary production was significantly impacted by DOC. In general, the effects of DOC on algal productivity was negative, although there was some evidence for the stimulation of whole ecosystem production by nutrients at low DOC concentrations. Epilimnetic chlorophyll, GPP, and community respiration increased significantly with DOC, and total depth integrated and sub-epilimnetic NPP decreased significantly with DOC. Lakes with the highest proportion of sub-epilimnetic production had well developed deep chlorophyll maxima (DCM). DCM were negatively correlated with DOC and are viewed as ecological hotspots for higher trophic levels. DCM and sub-epilimnetic productivity were eliminated in lakes with DOC values > 7.1 mg L-1. These results substantiate the influence of allochthonous DOC on aquatic food webs and highlight the combined effects of DOC on light and nutrient availability. The association of DOC with epilimnetic nutrients caused an increase in epilimnetic GPP (chapter 2) and decreasing light availability caused a decrease in total and sub-epilimnetic NPP (chapter 3). These contrasting effects of DOC on primary production provide further insight into the balance between nutrients and light with increasing concentrations of DOC.
Download or read book Dissolved Organic Carbon in Lakes written by Jeffrey Neil Houser and published by . This book was released on 2001 with total page 210 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Encyclopedia of Biodiversity written by and published by Academic Press. This book was released on 2013-02-05 with total page 5485 pages. Available in PDF, EPUB and Kindle. Book excerpt: The 7-volume Encyclopedia of Biodiversity, Second Edition maintains the reputation of the highly regarded original, presenting the most current information available in this globally crucial area of research and study. It brings together the dimensions of biodiversity and examines both the services it provides and the measures to protect it. Major themes of the work include the evolution of biodiversity, systems for classifying and defining biodiversity, ecological patterns and theories of biodiversity, and an assessment of contemporary patterns and trends in biodiversity. The science of biodiversity has become the science of our future. It is an interdisciplinary field spanning areas of both physical and life sciences. Our awareness of the loss of biodiversity has brought a long overdue appreciation of the magnitude of this loss and a determination to develop the tools to protect our future. Second edition includes over 100 new articles and 226 updated articles covering this multidisciplinary field— from evolution to habits to economics, in 7 volumes The editors of this edition are all well respected, instantly recognizable academics operating at the top of their respective fields in biodiversity research; readers can be assured that they are reading material that has been meticulously checked and reviewed by experts Approximately 1,800 figures and 350 tables complement the text, and more than 3,000 glossary entries explain key terms
Download or read book Coupling the Effects of Dissolved Organic Matter and Nutrient Stoichiometry with Nutrient Uptake in Boreal Forest Headwater Streams written by Dana Fjare and published by . This book was released on 2015 with total page 154 pages. Available in PDF, EPUB and Kindle. Book excerpt: Discontinuous permafrost affects the hydrology and distribution of vegetation in boreal forest watersheds, which in turn influence stream water chemistry. I investigated how loss of discontinuous permafrost with projected climate change might affect nutrient cycling in boreal forest headwater streams. I hypothesized that 1) the carbon, nitrogen, and phosphorus (C:N:P) ratio in dissolved organic matter (DOM) affects nutrient uptake due to stoichiometric constraints on autotrophic and heterotrophic nutrient assimilation, and 2) labile DOM affects nutrient uptake by increasing heterotrophic production. I tested my hypotheses using a series of instantaneous nutrient additions in nine headwater streams, with a factorial design manipulating both nutrient stoichiometry and DOM source. DOM was added as either acetate or leachate from birch leaves. Ambient nutrient uptake velocity (Vf-amb) was within the upper range of previously published literature values, ranging from 4.1-67.2 mm/min for N, 4.0-25.0 mm/min for P, and 4.2-34.5 mm/min for acetate. Uptake efficiency was similar for N and P added alone, in co-additions, and with DOM. Acetate and birch-DOM had similar effects on nutrient uptake, because both were sources of highly labile carbon. In 30-day laboratory bioavailability assays, birch and acetate-DOM exhibited ≥ 70% carbon loss. Vf-amb was in part explained by ambient stream chemistry, with Vf-amb for N weakly positively correlated with ambient P concentration, while Vf-amb for P and acetate was weakly negatively correlated with ambient N and ambient dissolved organic carbon, respectively. Consequently, inorganic nutrient availability may affect uptake of solutes as well as DOM lability. High demand for nutrients in boreal forest headwater streams suggests that uptake could increase concurrently with greater inorganic nutrient flux following a loss in permafrost extent.
Download or read book Impacts of Dissolved Organic Carbon on Productivity of Fish and Benthic Macroinvertebrates in North Temperate Lakes written by Nicola Craig and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: "Over the past several decades, increases in concentrations of dissolved organic carbon (DOC) have been observed in many north temperate aquatic ecosystems, a phenomenon known as aquatic 'browning', however the ecological consequences of this increase are not well understood. DOC from terrestrial sources stains lake water a dark brown color, and can have strong effects on the physical and biological structure of lake ecosystems. This occurs through its associated light and heat attenuating properties, which reduce thermocline depths, and thus the area of light, warm, and well-oxygenated habitat in DOC-rich lakes. Recent spatial surveys, where consumers were sampled from various lakes spanning a DOC gradient, have shown that fish productivity decreases along a gradient of increasing DOC, however the mechanisms behind this have not been fully explored. This thesis demonstrates potential mechanisms for this loss in productivity by determining how DOC affects zoobenthos, a primary prey item for many fish, as well as how DOC affects fish feeding efficiency and life history strategies.I begin by demonstrating, through the use of a spatial lake survey, that zoobenthos production declines over an increasing DOC gradient, and that this decline is due to limitations in oxygen-rich habitat availability, rather than the previously assumed mechanism of primary resource limitation. As many fish are visual predators, and high levels of DOC may reduce visibility, I then examined how DOC may affect fish feeding efficiency using mesocosm experiments and another gradient-based diet survey. I showed that bluegill (Lepomis macrochirus) feeding efficiency is not affected by DOC concentration, suggesting that these benthivores use cues other than vision to detect prey in darker, DOC-rich lakes. The reduction of fish productivity with increasing DOC is likely manifested through shifts in life history characteristics that are important to understand if we are to better manage fisheries with increasing browning. Again using bluegill as a model organism, I show that in low-DOC lakes, fish are able to attain enough energetic resources to reproduce as well as continue to grow after maturity. However, in high-DOC lakes, growth slows after maturity is reached, and so overall reproductive output and maximum size is reduced in these populations.Currently, the majority of studies focusing on the effects of DOC on consumer productivity are based on spatial gradient surveys, models, and mesocosm experiments. However, browning is a temporal process, and these studies may not accurately reflect how consumers may react to increases of DOC over time. In my final chapter, I describe a whole-ecosystem experiment were we divided a lake in two and increased DOC in one basin, comparing the effects on zoobenthos biomass and productivity to a reference basin, as well as the spatial survey from the first chapter. I show that, contrary to the results of the spatial survey, zoobenthos productivity actually increased with increasing DOC concentrations in this temporal experiment. This result suggests that there may be transitional effects of DOC increases on zoobenthos communities, and that the relationship between DOC and ecosystem productivity may be non-linear. This thesis highlights the need for multiple approaches in order to untangle the complex effects of DOC in lake ecosystems. The observations within will help us better predict how consumers in lake ecosystems may react in the face of future increases in DOC, and how to manage them accordingly. " --
Download or read book The Riverine Ecosystem Synthesis written by James H. Thorp and published by Elsevier. This book was released on 2010-07-27 with total page 233 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book presents the most comprehensive model yet for describing the structure and functioning of running freshwater ecosystems. Riverine Ecosystems Synthesis (RES) is a result of combining several theories published in recent decades, dealing with aquatic and terrestrial systems. New analyses are fused with a variety of new perspectives on how river network ecosystems are structured and function, and how they change along longitudinal, lateral, and temporal dimensions. Among these novel perspectives is a dramatically new view of the role of hydrogeomorphic forces in forming functional process zones from headwaters to the mouths of great rivers. Designed as a useful tool for aquatic scientists worldwide whether they work on small streams or great rivers and in forested or semi-arid regions, this book will provide a means for scientists to understand the fundamental and applied aspects of rivers in general and includes a practical guide and protocols for analyzing individual rivers. Specific examples of rivers in at least four continents (Africa, Australia, Europe and North America) serve to illustrate the power and utility of the RES concept. Develops the classic, seminal article in River Research and Applications, "A Model of Biocomplexity in River Networks Across Space and Time" which introduced the RES concept for the first time A guide to the practical analysis of individual rivers, extending its use from pristine ecosystems to modern, human-modified rivers An essential aid both to the study fundamental and applied aspects of rivers, such as rehabilitation, management, monitoring, assessment, and flow manipulation of networks
Download or read book Assessing the Ecological Effects of Increased Dissolved Organic Carbon in Maine Lakes Over Recent Decades written by Robert E. Brown and published by . This book was released on 2014 with total page 112 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Determining Sources of Dissolved Organic Carbon and Nutrients in an Urban Basin Using Novel and Traditional Methods written by Krittika Govil and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Water quality in urban ecosystems is sensitive to localized disturbances potentially affecting those mechanisms which influence nutrient cycles. The Carters Creek Basin has been reported to have elevated concentrations of dissolved organic carbon (DOC). In combination with high terrestrial nutrient export from non-point sources and point source effluent discharge, this has been suggested to contribute to E.Coli recovery and regrowth. Spatial identification of loading "hot-spots" or locations of elevated nutrient concentrations of non-point, terrestrial sources may provide critical information necessary for appropriate mitigation efforts and watershed management. This study used traditional and novel methods for source tracking nutrients and dissolved organic carbon in small urban and rural watersheds in Brazos County, Texas. A nested watershed approach allowed identification of problem areas of nutrient loading. A novel cost-effective technique using diffuse reflectance near-infrared spectroscopy was used to identify sources of DOC. Monthly stream sampling was conducted at 12 sites from 2012 to 2013. Impacts of human activity on landscape features determining source pathways for nutrient retention, transport, and conversion were identified in this study. Higher nitrate-N (0.12-22.8 mg L−1), orthophosphate-P (0.11-3.60mgL−1), and DOC concentrations (18.6-68.1 mg L−1) were found across the watershed than in 2007. Factors such as increased erosion, sodic soil dispersion, land use, and flow conditions wereidentified as possible causes for increased carbon (C), nitrogen (N) and phosphorus (P) observed in the basin. This study supported the use of near-infrared spectroscopy to elucidate watershed sources of carbon. The major sources of DOC into the Carter Creek basin watersheds were leachate from soil and turfgrass. Rural subwatersheds had less complicated source signatures than their urban counterparts. Urban impervious runoff signatures also clustered with stream water signatures, especially during high flow in October and September. These results indicate that specific vegetation such as turfgrass used for landscapes in urban watersheds coupled with sodic irrigation may alter traditional nitrogen, phosphorus and carbon cycling in urbanizing watersheds. Spatial source tracking will enable efficient pollution mitigation and protect water quality as a result of this study. The electronic version of this dissertation is accessible from http://hdl.handle.net/1969.1/152459
Download or read book The Effect of In line Lakes on Dissolved Organic Matter Dynamics in Mountain Streams written by Keli J. Goodman and published by . This book was released on 2010 with total page 183 pages. Available in PDF, EPUB and Kindle. Book excerpt: This research combines observation, experimentation, and modeling to evaluate the influence of lakes on dissolved organic matter (DOM) quantity, quality and export in subalpine watersheds of the Sawtooth Mountain Lake District, central Idaho. First, I conducted an empirical study of the hydrologic and biogeochemical controls on DOM dynamics in stream-lake fluvial networks. I hypothesized that lakes would decrease temporal variability (i.e., buffer) and alter the characteristics of DOM from inflow to outflow. I tested these hypotheses by evaluating DOM temporal patterns and measuring annual export in seven-paired lake inflows and outflows. I then evaluated how ultraviolet (UV) exposure affected DOM characteristics during snowmelt and baseflow, and how UV alters baseflow DOM bioavailability and nutrient limitation. Given that increased water residence time increases UV exposure, I hypothesized that lake outflow DOM would be more photorecalcitrant than DOM from lake inflows. I further hypothesized that UV exposure would increase DOM quality, heterotrophic processing, and nutrient demand. Results indicate that lakes can buffer stream temporal variability by acting as a DOM sink during snowmelt and a DOM source during baseflow. Lake outflow DOM photodegradation was similar to lake inflows during snowmelt (p=0.66). Conversely, outflow DOM was 2X more photorecalcitrant than inflow DOM during baseflow (ANOVA, p=0.03) and was strongly related to water residence time (WRT). During baseflow, light exposure increased inflow and outflow DOM bioavailability (p=0.059 and 0.024, respectively) and nutrient limitation (p=0.03 and 0.09, respectively). Combined, these results indicate that WRT in subalpine lakes strongly influences DOM temporal variability and DOM degradation and processing. Thus, lakes can provide temporal stability of DOM and potentially increase both carbon and nutrient uptake by heterotrophs in lake outflows. I then evaluated how global changes could alter hydrologic and nutrient dynamics in a subalpine lake. Model results indicate that the magnitude and timing of snowmelt runoff can have a substantial effect on water and nutrient exports. In phosphorus (P)- limited lakes, increases in inorganic N concentrations within and exported from lakes are likely to occur with increased temperatures and lake WRT. Increases in atmospheric N deposition will further enhance inorganic N exports in P-limited subalpine lakes.
Download or read book Microbial and Photochemical Cycling of Dissolved Organic Matter in Boreal Headwater Streams written by Doreen Franke and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Dissolved organic matter (DOM) is a key global energy source and carbon reservoir that links terrestrial and aquatic biogeochemical cycling. Allochthonous organic matter is abundant in boreal headwater streams, and environmental changes such as variation in nutrient availability and changes to watershed landscape composition have great potential for altering the DOM source, its composition and cycling. This dissertation focuses on two of the main drivers of aquatic carbon and nutrient cycling: the photochemical and the microbial processing of DOM in boreal headwater streams; specifically (i) how the photochemical lability of DOM varies between reaches within headwater streams, among headwater streams and an associated large river reach, (ii) how stream biofilm mineralization may be regulated by watershed organic matter source and composition, increased labile carbon, nitrogen, and phosphorus availability, and (iii) whether algal carbon sources are important to supporting stream biofilms and if such sources influence the use of allochthonous DOM in nutrient-enriched streams. The results suggest changes in landscape and nutrient availability have the potential to alter the photochemical and biogeochemical cycling of DOM. DOM photolability was increased upstream relative to downstream and the river DOM. This may be due to differences in DOM source and composition, and suggests losses in photolabile DOM downstream and in the lower reaches of the watershed. The phototransformation of DOM into low molecular weight compounds and nutrients such as ammonium is likely relevant to the carbon and nutrient cycling in boreal watersheds. Results here further suggest that boreal stream biofilm mineralization of DOM is regulated by watershed DOM source and composition. Labile carbon sources, such as algal inputs, may also play an important role in regulating DOM mineralization and the processing of nutrients by these biofilms. In nutrient-impacted streams, where primary production is high relative to nutrientpoor streams, biofilms may be stimulated to incorporate algal carbon sources. Yet in the boreal streams studied here, added labile carbon rarely enhanced the mineralization of extant stream DOM suggesting autotrophic-heterotrophic interactions represent a more important priming effect relative to changing DOM source in boreal streams.
Download or read book Sources and Cycling of Dissolved Organic Carbon Across a Landscape of Arctic Delta Lakes written by Suzanne E. Tank and published by . This book was released on 2009 with total page 434 pages. Available in PDF, EPUB and Kindle. Book excerpt: Dissolved organic carbon (DOC) is a key regulator of aquatic ecosystems, and the primary substrate for aquatic bacteria. However, variations in function between different DOC sources are rarely studied. Arctic Mackenzie Delta lakes exhibit striking differences in DOC composition, with DOC sources ranging from C produced as a byproduct of aquatic plant (macrophyte) photosynthesis, to C derived from permafrost melting (thermokarst), and C delivered to lakes via river-water. This study assessed how variations in DOC source regulate the composition of the within-lake pool, drive bacterial metabolism and the contribution of bacterial biomass to higher trophic levels, and affect CO2 flux from Delta lakes. DOC-specific tracers showed macrophyte-derived DOC to comprise less than 15% of the DOC pool in macrophyte-rich lakes, despite macrophyte C levels 7-12-fold greater than total DOC. However, bacterial 13C indicated that bacteria preferentially incorporate DOC generated by macrophytes, while surveys and incubation experiments showed that bacterial metabolism is rapid on macrophytic DOC, with high rates of bacterial biomass production relative to respiratory loss as CO2. Accordingly, 13C, 15N, and fatty acid biomarkers demonstrated that zooplankton from macrophyte-rich lakes receive a greater proportion of their biomass from bacterial organic matter than zooplankton from other lake types. At the same time, however, experiments indicated that the high pH resulting from rapid photosynthesis in macrophyte-rich lakes can decrease the rate of bacterial metabolism over the short-term, and increase CO2 respiration at the expense of bacterial biomass production. In contrast, DOC-specific tracers indicated that thermokarst-derived DOC accumulates in lakes. Incubation experiments and In situ surveys revealed thermokarst DOC to be a relatively poor bacterial substrate, which resulted in proportionately more CO2 respiration, relative to bacterial biomass production, than observed for other Delta DOC sources. Moreover, multi-year surveys demonstrated that thermokarst lakes exhibit high levels of CO2 emission, despite clear undersaturation in other lakes, presumably because permafrost-derived DOC was largely respired by bacteria. Understanding the divergent roles played by the contrasting sources of DOC to Delta lakes both adds insight to the functioning of other lake regions, globally, and helps clarify the effect of climate-induced changes in DOC on northern lakes.
Download or read book Sources and Cycling of Nutrients and Dissolved Organic Carbon in the Lower ACF Basin and Lake Seminole written by Julie Marie McEntire and published by . This book was released on 2009 with total page 260 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Dissolved Organic Matter and Lake Metabolism Technical Progress Report 1 July 1979 30 June 1980 written by and published by . This book was released on 1980 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Progress in research to evaluate the impact of utilization of fossil fuels on surface water is reported. Analyses of regulatory mechanisms of growth and rates of carbon cycling center on evaluation of quantitative control interactions among the microflora of the pelagial zones of several lakes of progressively greater eutrophy, littoral photosynthetic producer-decomposer complex, and allochthonous inorganic-organic influxes and their biotic processing. The underlying thesis is that quantification of the dynamic carbon fluxes among these components and their rate control mechanisms by physical and chemical factors are fundamental to elucidation of the rate functions of lake eutrophication. A major portion of the research has been directed towards the fate and nutrient mechanisms regulating qualitative and quantitative utilization and losses of organic carbon synthesized within lakes and their drainage basins. It has become increasingly apparent that the wetland and littoral flora, and attendant epiphytic and benthic microflora, have major regulatory controls on biogeochemical cycling of whole lake systems. A major effort on factors regulating the metabolism of littoral macrophytes and attached algae has been coupled to integrated studies on their decomposition and the fate of detrital dissolved and particulate organic matter. These organic products are being coupled to influences on enzymatic activity and inorganic nutrient cycling.
Download or read book Historisches und aktuelles aus Psychiatrie und Neurologie written by and published by . This book was released on 1968 with total page 171 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Dissolved Organic Matter and Lake Metabolism written by Robert G. Wetzel and published by . This book was released on 1984 with total page 88 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Controls on Microbial Processing of Dissolved Organic Matter in Boreal Forest Streams written by Marie Schmidt and published by . This book was released on 2020 with total page 128 pages. Available in PDF, EPUB and Kindle. Book excerpt: In the boreal forest, permafrost thaw is resulting in changes in vegetation and deepening of watershed flowpaths. Caribou-Poker Creeks Research Watershed contains sub-catchments underlain with varying permafrost extents (4-53% cover), providing the opportunity to study how permafrost extent affects water chemistry and nutrient cycling. I measured nitrogen (N), phosphorous (P), and carbon (C) processing ectoenzyme activity in the water column and sediment of headwater streams, and related ectoenzyme activity to nutrient and dissolved organic carbon (DOC) concentration. Additionally, I used nutrient diffusing substrata (NDS) to grow biofilms with enhanced inorganic N and P and labile C alone and in combination and measured ectoenzyme activity and respiration of biofilms in response to resource amendments. High P-processing enzyme activity across streams of the CPCRW indicated microbial P limitation. Respiration and organic matter processing enzymes of biofilms grown on NDS increased with labile C or labile C in combination with nutrient additions, implying that labile C limited or co-limited rates of DOM processing. Our results suggest that as climate warming and subsequent permafrost thaw alters terrestrial inputs of dissolved organic matter (DOM) and inorganic nutrients into streams, changes in inorganic P and labile C availability will control microbial processing of DOM.
